Posted by: Bystander PJ18 JUN 2010
You must have seen one or more of those old cowboy movies in which the baddie goes for his gun but ends up being shot himself because of his opponent’s lightning reaction. The physicist and Nobel laureate Niels Bohr had a theory that we intuitively respond to threats in our environment faster than we can initiate a threat.
He apparently tested his theory in toy pistol fights with a colleague. Bohr always took the reactive role himself and always won. But that does not, of course, prove his theory, since he might just have had greater skill and a faster reaction time than his colleague anyway.
Although Bohr died nearly 50 years ago, his theory has only recently been put to the test in controlled conditions. Backed by funding from the Biotechnology and Biological Sciences Research Council and the Wellcome Trust, researchers at the University of Birmingham have conducted “laboratory gunfights” to test the theory.
The research has demonstrated that we do indeed move faster when reacting than when initiating an action. However, the greater speed would be unlikely to help in a real gunfight, since on average the reacting participant executed the movement only 21 milliseconds faster than the initiating participant.
Team leader David Welchman is not put off by this tiny advantage. He suggests that although 21 milliseconds probably would not save you in a Wild West duel, it could mean the difference between life and death when you are trying to avoid an oncoming bus.
The research team is now interested to know whether the difference means that the two types of action involve different brain processes. There might be some evidence for this in people with Parkinson’s disease, who find intentional movements far more difficult than reactive ones.
For example, although a patient asked to pick up a ball from a table may have difficulty doing so, he may have no trouble catching a ball thrown at him.
If it turns out that Parkinson’s disease does indeed affects areas of the brain that contribute to intentional actions rather than reactive ones, this finding might offer possibilities for developing strategies to ease movement in such patients.